Apparatus and method for diagnosing flaws in rotor of indcution motor, and medium on which is recorded computer-readable program for executing method

Abstract

The invention relates to an apparatus and method for diagnosing flaws in the rotor of an induction motor, and to a medium on which is recorded a computer-readable program for executing the method. The apparatus for diagnosing flaws in the rotor of an induction motor comprises a voltage supply unit, a current measuring unit, a reactance computing unit, and an eccentricity diagnosing unit. The voltage supply unit supplies a single-phase voltage to the induction motor. The current measuring unit measures the current supplied to the induction motor due to the supplied voltage. The reactance computing unit computes the reactance of the induction motor by using the voltage supplied to the motor and the measured current during the rotation of the rotor of the induction motor. The eccentricity diagnosing unit diagnoses that the induction motor air gap is eccentric if the reactance value computed during one revolution of the rotor of the induction motor is always greater than a predetermined reactance value. By virtue of this arrangement, the apparatus for diagnosing flaws in the rotor of an induction motor according to the present invention may be applied to any type of an induction motor, thereby facilitating the diagnosis of induction-motor eccentricity even without additional expensive equipment.

Description

technical field [0001] The present invention relates to an electric device, and in more detail, relates to a device and method for diagnosing the state of a motor. Background technique [0002] figure 1 It is a figure which schematically shows the structure of an induction motor. Such as figure 1 As shown, in the induction motor, voltage and current are applied to the winding 3 of the stator, so that the magnetic flux Φ generated in the stator core 1 s A current is generated on the bar 4 of the squirrel-cage rotor 2, thereby generating a magnetic flux Φ r . [0003] At this time, if an input power supply with a phase difference of 120° is applied to the three-phase winding of the stator, the stator magnetic flux Φ s It will rotate at a certain speed according to the input power, which is called a rotating magnetic field. [0004] The squirrel-cage motor operates by torque τ induced based on the mutual relationship between the magnetic flux generated in the stator and t...

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Problems solved by technology

[0032] However, in the case of low-frequency components, it can only be diagnosed when mixed eccentricity is present. High-frequency components are usually more suitable for static, dynamic, and mixed eccentric faults than low-frequency components. However, the number of rotor slots (R) needs to be known, and specific faults cannot be detected. Defects when the number of poles - the number of rotor slots (p-R relation)

[0033] Moreover, this frequency analysis method needs to store a large amount of data. If the load changes during operation and the speed and slip change, it is difficult to detect the accurate fault frequency.

In addition, due to the influence of a specific load (load torque oscillation), when the eccentric frequency of the gap overlaps, it also has the disadvantage of being difficult to distinguish

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